Various means have been used in the past to control the flow of a fluid from a nozzle. In almost all of the prior art designs, the operator on the remote control device operating the valve had to work against the line pressure. In high pressure flow control devices, such as fire nozzles, large forces are frequently required in order to control the flow-setting of the valve. Even prior art small garden hose nozzles are difficult to adjust, when varying the nozzle spray pattern, due to the force on the valve caused by the fluid pressure in the line. Prior art large fire hose adjustable spray nozzles generally require several men to hold and control the position of the nozzle because of the large force needed to overcome the combination of the reaction forces of the jet stream and the line pressure on the valve. In order to overcome these large forces resisting valve movement prior art adjustable nozzles generally required the use of massive valve designs, lever type mechanisms, line type glove and gate valves with massive stems and handles, all of which are frequently complex to design, expensive to fabricate and difficult to operate.
The present invention greatly furthers the state of the art disclosed in the U.S. Pat. No. 2,799,466. The present device provides for an infinitely variable controlled flow from the valve full open to full closed position. In contradistinction the above referenced patent is forced to an either completely "on" or completely "off" position. The present invention utilizes a cam-control pin combination, operatively positioned within the nozzle body and the piston valve, to adjust the fore and aft pressure on the piston valve, to reach an equilibrium pressure thereon, which will hold the piston valve at any intermediate position desired. In the present instance the piston valve has a fluid bypass passageway therethrough and a valve seat therein which cooperates with the cam controlled control pin to adjustably close or open the bypass passageway to control the pressure forces acting on the piston gate and thus the movement thereof.